Currently the three iPhones wirelessly charge at a rate of 5 watts, but the iOS 11.2 update allows them to charge at a rate of 7.5w, which is a 50 percent increase. The charging update was spotted and tested out by MacRumors.

Although wireless charging is new to the iPhone, it's been around on Android devices for several years. iPhones use the Qi wireless charging standard, which maxes out at a rate of 15w. Samsung's Galaxy Note 8, for example, supports 15-watt fast wireless charging.

You won't need to buy a new charger to take advantage of faster speeds. The Mophie and Belkin wireless chargers that Apple sells are already capable of delivering 7.5w of power. Apple has said on the chargers' listings since their releases that it will enable "fast wireless charging" with a later software update -- it's likely that iOS 11.2 is that update.

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Apple is also planning on releasing its own wireless charging mat, AirPower, that's designed to charge multiple Apple products at once. It isn't clear if AirPower would use the faster charging speeds.

To push those charging speeds, the iPhone X, 8 and 8 Plus will charge even faster with a USB-C to Lightning cable setup. The configuration requires buying a handful of accessories, but it can reach top charging speeds if you don't mind the wires. If you want to stay wireless, you're stuck at 7.5w for now.